I have used this process a number of times and it works. It is a two step etch process for the stencil manufacturer, but like I said I have used this on similar issues about 6 - 8 years ago and had good results. John Burke (408) 515 4992 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Braddock, Iain (UK) Sent: Thursday, June 18, 2009 12:35 AM To: [log in to unmask] Subject: Re: [TN] SolderMask Question One option may be that you identify in your Gerber file the areas causing problems ie. raised and have your solder stencil relieved on the bottom side to allow clearance in these areas, that way the stencil would lie flush when printing.....just a thought! Iain. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Vargas, Stephen M Sent: 17 June 2009 17:22 To: [log in to unmask] Subject: [TN] SolderMask Question *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. All: We have a Class III PCB, that we are building using leaded technology (non-RoHS), HASL finish, where my customer is specifying double masking over vias for "via protection". Dry film is initially being placed over the vias only, then the board is covered by LPI. Our problem is that it creates problems with the solder stencil not properly gasketing to the PCB during screen-printing resulting in solder defects. We are seeing raised solder mask as high as .003". Is this (double masking) commonplace? Are there more "manufacturing friendly" options for optimum via protection? I've asked about possibly using dry film mask only (no LPI on top), but was told that the mask feature sizes are too small for dry film. Any insight would be appreciated. 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